Environmental Response Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22 Suehirocho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology, 181 Ipsin-gilJeollabuk-do, Jeongeup, 56212, Korea.
Sci Rep. 2021 Oct 26;11(1):21109. doi: 10.1038/s41598-021-00564-4.
Cesium (Cs) is found at low levels in nature but does not confer any known benefit to plants. Cs and K compete in cells due to the chemical similarity of Cs to potassium (K), and can induce K deficiency in cells. In previous studies, we identified chemicals that increase Cs tolerance in plants. Among them, a small chemical compound (CHFNO), named CsToAcE1, was confirmed to enhance Cs tolerance while increasing Cs accumulation in plants. Treatment of plants with CsToAcE1 resulted in greater Cs and K accumulation and also alleviated Cs-induced growth retardation in Arabidopsis. In the present study, potential target proteins of CsToAcE1 were isolated from Arabidopsis to determine the mechanism by which CsToAcE1 alleviates Cs stress, while enhancing Cs accumulation. Our analysis identified one of the interacting target proteins of CsToAcE1 to be BETA-GLUCOSIDASE 23 (AtβGLU23). Interestingly, Arabidopsis atβglu23 mutants exhibited enhanced tolerance to Cs stress but did not respond to the application of CsToAcE1. Notably, application of CsToAcE1 resulted in a reduction of Cs-induced AtβGLU23 expression in wild-type plants, while this was not observed in a high affinity transporter mutant, athak5. Our data indicate that AtβGLU23 regulates plant response to Cs stress and that CsToAcE1 enhances Cs tolerance by repressing AtβGLU23. In addition, AtHAK5 also appears to be involved in this response.
铯（Cs）在自然界中的含量很低，但对植物没有任何已知的益处。由于 Cs 与钾（K）在化学性质上相似，Cs 和 K 在细胞中会产生竞争，从而导致细胞中的 K 缺乏。在之前的研究中，我们鉴定出了一些能够提高植物对 Cs 耐受性的化学物质。其中，一种名为 CsToAcE1 的小分子化合物被证实能够增强植物对 Cs 的耐受性，同时增加植物对 Cs 的积累。用 CsToAcE1 处理植物会导致 Cs 和 K 的积累增加，并缓解 Cs 对拟南芥生长的抑制。在本研究中，我们从拟南芥中分离出 CsToAcE1 的潜在靶蛋白，以确定 CsToAcE1 缓解 Cs 胁迫、同时增强 Cs 积累的作用机制。我们的分析确定了 CsToAcE1 的一个相互作用靶蛋白是 BETA-GLUCOSIDASE 23（AtβGLU23）。有趣的是，拟南芥 atβglu23 突变体对 Cs 胁迫的耐受性增强，但对 CsToAcE1 的应用没有反应。值得注意的是，在野生型植物中，CsToAcE1 的应用导致 Cs 诱导的 AtβGLU23 表达减少，但在高亲和力转运体突变体 athak5 中没有观察到这种情况。我们的数据表明，AtβGLU23 调节植物对 Cs 胁迫的反应，而 CsToAcE1 通过抑制 AtβGLU23 增强植物对 Cs 的耐受性。此外，AtHAK5 似乎也参与了这一反应。
